Mains filters
 

In article , Arny Krueger
writes
"tony sayer" wrote in message

Rane, a U.S. pro audio gear manufacturer with a very
solid reputation for conservative technology claims that
some of their gear (like mic preamps) showed a SNR
advantage when the power transformer was moved out of
the box and into a big plastic wart on the power cord.

http://www.rane.com/rap.html

Reasons to use external pwoer supples:

"Better Audio Performance. Removes the hum source, i.e.
the AC line transformer and all primary circuits
resulting in quieter noise performance, without the
usual (and annoying) 50/60 Hz and 150/180 Hz hum
components."

More bollockx.

**** poor design then, if their having those problems.

Mic preamps for audio production are a more stringent environment than say,
RIAA phono preamps. RIAA MM phono preamps have 40 dB gain at 20Hz, but their
noise bandwidth is only 50 Hz. Mic preamps typically have up to 60 dB of
gain, and a minimum of 20 KHz noise bandwidth, usually far more.

Arny surely your not saying that they can't design a mic amp without a
built in AC PSU now are you?....

This "wall-wart" caper is more to do with complying with
different regs in different markets...

That, too.



--
Tony Sayer

Mains filters
 

On Thu, 16 Mar 2006 09:10:30 +0000, Glenn Richards
wrote:

Don Pearce wrote:

I ask a serious question, expecting some sensible responses, and
instead all I get are sarcastic comments.
No, you were trolling.

No, I was asking a serious question.

As reducing the noise floor (by whatever means) improves dynamics.
And this I have tested, I've recently been involved in cleaning up
some recordings made about 25 years ago on analogue equipment. This
process involves re-EQ followed by digital noise reduction, and the
results before and after applying the noise reduction are nothing
short of dramatic.
Cleaning up recordings most certainly does *not* involve eq. That
would be changing recordings.

By "cleaning up" I was referring specifically to applying digital noise
reduction. The re-EQ was mentioned simply for completeness, as the
recordings were a bit bass-shy and lacking in sparkle. So a touch of
smiley EQ solves that, followed by noise reduction.

It's rather vital that you EQ before NR though, otherwise the re-EQ
boosts bits that the NR has cut, leading to some interesting pumping
effects...

Read above - you can filter the mains til you turn blue and you won't
change your noise floor by even a milli dB.

On an average setup in an average domestic residence I'm sure that's the
case. Unfortunately I have a dozen or so PCs, all with switching power
supplies, sat in the next room, spewing RF onto the ring main. Which in
theory could be affecting the sound... at least in theory.

Turn your amplifier on, with no music playing and listen. Leave the
volume control in the normal listening position and sit in your
listening chair. What can you hear? Anything? Of course not. And what
little hiss there is comes from the front end of the amplifier. None
of it comes from the mains.

You can't hear much above 20kHz. But signals at frequencies above this
will affect what you do hear, harmonics, interaction etc. Why do you
think there's been so much work done on DVD-A, SACD etc, using sample
rates of 96kHz or even 192kHz, rather than 44.1?

Good old Russ Andrews - he has successfully conned £250 out of you.

Read my earlier postings. Currently I'm just using a standard IEC cable,
running into a surge protected (not even an RFI filtered) 4-way strip.
Surge protected for obvious reasons... I don't want a rogue power spike
frying 2 grand's worth of kit.

Now wise up and stop waving your stupidity like a flag of honour.

You are Stewart Pinkerton and I claim my five pounds.

No he's not, but an understandable error. I've been staying out of
this thread because Don is saying exactly what I would say. BTW, mains
cable works very well for conducting HF, all you have to do is
determine the characteristic impedance, and couple your kit to it with
suitable impedance matchers.

As you said (but didn't actually apply) it's just basic engineering
knowledge.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

On Thu, 16 Mar 2006 14:17:15 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Don Pearce wrote:
You've never heard things like a fridge splat etc which is mains borne?
Of course it depends on the design of the power supply in your amp, etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

No - never heard a thing come through the mains. If I started hearing
stuff now, I wouldn't be buying mains filters - I'd be fixing the
wiring.

Hmm. Switch off an inductive load like a motor on the same ring as an amp
and you'll hear it - or at least be able to measure the spike.

On the mains, certainly - not at the speaker terminals.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

On Thu, 16 Mar 2006 09:14:39 +0000, Glenn Richards
wrote:

Don Pearce wrote:

The problem is that this is a ghost that has been laid now many times,
and every so often somebody comes along and insists on digging it up
again, usually with some piece of pseudo science to back it up

Just a thought...

If I were to replace my Ethernet cables with triple-shielded OFC, and
use a £250 IEC cable to connect my PC to the mains, do you think it
would lower the noise floor in this group?

Definitely, if you were so busy doing it that you didn't post.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

On Thu, 16 Mar 2006 13:13:38 +0000, Glenn Richards
wrote:

Roderick Stewart wrote:

In a conversation I had with a friend, we determined that power
cables are good at carrying low frequencies, and poor at carrying
higher frequencies. So RFI picked up at the substation won't make
it to your house, but interference sources in your house will cause
RFI to reach your kit.
How do you determine the electrical properties of cables by
conversation?

By applying known principles of engineering.

The losses at high frequencies are significantly higher in 2.5mm mains
wiring cable than screened co-ax, if you don't believe me try running a
composite video signal down mains cable (rather than 75ohm co-ax) and
see how far you get.

Just as far as you would with coax, if you match impedance properly
and don't mind some intereference.

It's like saying "how can you determine that an Audi Quattro is going to
go around a hairpin bend at 100mph faster than a Ford Fiesta", for example.

Indeed, but a poor analogy, since neither car will achieve this. Lack
of engineering knowledge noted yet again........

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

On Thu, 16 Mar 2006 10:47:44 +0000, Glenn Richards
wrote:

Don Pearce wrote:

So for goodness sake stop posting stuff that is trying to sound like
engineering when it is in fact unmitigated balls. I already told you,
it is no longer funny. Stick to whatever it is you know about.

So the bottom line is that you don't believe RFI filtering will make a
difference.

Why didn't you just say that? Why did you have to resort to posting all
that crap, in response to what was quite a serious question?

I suspect that was because you posted a pile of unmitigated ********.

What really is no longer funny is that when one posts a question or
observation on this group that doesn't quite fit within the narrow
viewpoints of certain people that think they own and run this newsgroup,
all hell breaks loose, making it impossible to have a civilised
discussion about anything at all. Because there's always someone who
will disagree with subject "x" enough to start hurling personal insults
around.

When you post bull****, there's a fair chance that those who know what
they're talking about will point out your errors. Tough.

If your opinion is that filtering won't make a difference, state your
opinion, avoid personal insults, and let civilised debate commence.

It won't, if your gear has decent RFI rejection, as it certainly
should. Moral of the tale - avoid 'high end' gear from back street
companies with no real engineering ability.

Sadly there doesn't appear to be a uk.rec.hi-fi where those of us who
can tell the difference between bell wire and 105-strand speaker cable
can have a discussion about which cable sounds best with which
equipment, without the likes of yourselves or Pinkerton (to name but
two) chiming in with "********" or words to that effect. We've got
uk.rec.audio.vinyl now, why not have uk.rec.audio.hi-fi or audiophile as
well?

Your problem is that you're a pathological liar who refuses to admit
that he can *not* tell the difference between cables by sound alone.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

On Thu, 16 Mar 2006 15:14:16 +0000, Glenn Richards
wrote:

Jim Lesurf wrote:

That mains filters may be useful if you are having a problem with
audible 'clicks and pops' from the mains, and can't suppress them at
source.

What about inaudible RF interference, for example from a PC PSU?

I know all about the regulations... but I've opened enough of these
things up to know that they often radiate like a spark transmitter.

Sure they do, that's why you should keep the box closed - duuhh.

Ideally, though, the audio equipment is well enough designed to
prevent such problems being audible.

In an ideal world, yes... but even kit like my Arcam stuff is still
built to a budget. I've had long conversations with R&D bods from
companies like Arcam, Meridian etc at hi-fi shows, and they're always
cursing the beancounters... "we wanted to put more RFI filtering in, but
budget constraints meant we had to make sacrifices" etc etc.

That is a flat lie, no one from Arcam or Meridian said any such thing.

However, simply chainging 'mains cable' with no filter or surge
suppressor is probably a waste of effort.

Yup... if you replaced your IEC cable with 3-core braided cable with
screening, all you'd be doing is making sure the RFI got from one end to
the other with minimal losses!

Been doing a bit of research today, and I've located something called an
Isotek cable. A friend at Sevenoaks hi-fi has offered to bring one
around (the one they use in their demo room) to find out if it makes a
difference, and if so, how it works, what type of filter it uses etc.

I've managed to source some braided 3 core screened cable that's rated
for mains use and only costs about £4/m, filtered plug less than £2, IEC
line socket about £1.20. If it does make a difference, I'm going to have
a go at making my own for about 8 quid instead of the 60 quid an Isotek
cable costs. Then sell my own ones for 50-60 quid. ;-)

Will post the results of my testing after the weekend - I can't get hold
of the loan cable until Sunday as they'll need it in the demo room on
Saturday.

Oh Jeez, I can't wait for *more* of your cable bull****! :-(

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Mains filters
 

"Stewart Pinkerton" wrote in message
...
On Thu, 16 Mar 2006 14:17:15 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Don Pearce wrote:
You've never heard things like a fridge splat etc which is mains borne?
Of course it depends on the design of the power supply in your amp,
etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

No - never heard a thing come through the mains. If I started hearing
stuff now, I wouldn't be buying mains filters - I'd be fixing the
wiring.

Hmm. Switch off an inductive load like a motor on the same ring as an amp
and you'll hear it - or at least be able to measure the spike.

On the mains, certainly - not at the speaker terminals.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

You could well get a sharp crack coming through the 'speakers. It would
depend on the amplifier's design, whether it had a filter on its mains input
and whether the amplifier design had sufficient power supply rejection.

S.

Mains filters
 

"tony sayer" wrote in message
...

Yes please publish it here for all the see, and see also what snake oil
he used to do that with.

Total bollockx!.....
--
Tony Sayer

OK Tony and the Gang! For your hedification:


Off their site!..


"The HTS 5100 is designed for the home theater enthusiast with a passion
for picture and sound quality. The Home Theatre Reference PowerCenterT
HTS 5100 features Clean PowerT Stage 4 v2.0 filter circuitry to prevent
AC power line noise from disturbing component performance. Five separate
filters give you maximum quality sound and picture. TVs will deliver a
razor sharp picture with the most vivid color detail and contrast
possible. Audio jumps from the speakers with 3-D realism, delivering
amazing clarity, pinpoint imaging, and precise soundstage".



Sez it all really!...

Total ********!....


This bloke related to Russ A perchance?..



Monster Power type HTS 2600.
This is one of the midprice units at about EUR 400 trade.
and about EUR 590 retail.

http://www.monstercable.com/power/lineRefPower.asp

I have just spoken with the main dealer. They have no
stock, and demand outstrips supply.

More ********....


The analyser box to which I referred is not on sale through
retailers, though I have seen them previously.

Oh!, go on please, entertain us do;-)


It is termed "Wide Band Power Analyser" and made in
either the UK or the US by a company called Entec.

Wideband power analyser eh!, Bet the BBC have bought them all up;!...

I don my flameproof overalls and retire swiftly to
a neutral corner.

Yes perhaps you should go and see someone!.

keyword is in the sentence a few lines above;(......

Over to you.
Iain



Hello Tony.

You asked me to post details of the unit which I had seen.
To meet your request I did this, without an opinion or an
interest eith for or against.

Since then I have been able to find out the sales figs for
the Scandi countries. I am told the highest sales within the EU
are to the UK. There is a "huge" mark-up. So someone is making
a pile of cash. From your bitterness, I deduce it is not you:-))

Iain

Mains filters
 

"tony sayer" wrote in message

In article
, Arny
Krueger writes
"tony sayer" wrote in message

Rane, a U.S. pro audio gear manufacturer with a very
solid reputation for conservative technology claims
that some of their gear (like mic preamps) showed a SNR
advantage when the power transformer was moved out of
the box and into a big plastic wart on the power cord.

http://www.rane.com/rap.html

Reasons to use external pwoer supples:

"Better Audio Performance. Removes the hum source, i.e.
the AC line transformer and all primary circuits
resulting in quieter noise performance, without the
usual (and annoying) 50/60 Hz and 150/180 Hz hum
components."

More bollockx.

**** poor design then, if their having those problems.

Mic preamps for audio production are a more stringent
environment than say, RIAA phono preamps. RIAA MM phono
preamps have 40 dB gain at 20Hz, but their noise
bandwidth is only 50 Hz. Mic preamps typically have up
to 60 dB of gain, and a minimum of 20 KHz noise
bandwidth, usually far more.

Arny surely your not saying that they can't design a mic
amp without a built in AC PSU now are you?...


It's not a matter of not being able to design an acceptable preamp with an
internal transformer, its a matter of the ultimate performance of similar
preamps that differ only in the location of the power transformer.